Montelukast for asthma Singulair

Last updated by Peer reviewed by Sid Dajani
Last updated Meets Patient’s editorial guidelines

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Take montelukast regularly every evening.

Your doctor will prescribe a reliever inhaler for you to use in case you have an asthma attack. Make sure that you keep it with you all the time.

The most common side-effects of montelukast are respiratory infections, tummy (abdominal) pain and headache.

Type of medicineA leukotriene receptor antagonist
Used forAsthma
Also calledSingulair®
Available asTablets, chewable tablets (for children), and sachets of granules (for children)

Asthma is a common condition caused by inflammation in the smaller airways of the lungs. The inflammation irritates the muscles around the airways and causes them to constrict. This causes your airways to narrow. It is then more difficult for air to get in and out of your lungs. This causes the typical symptoms of wheeze, chest tightness and shortness of breath. The inflammation also causes the lining of your airways to make extra mucus which causes coughing.

Asthma symptoms can flare up from time to time and there may be no apparent reason why. However, some people find that symptoms are made worse by triggers such as exercise and pollen. These things cause your body to produce chemical substances called leukotrienes, which cause the inflammation. Montelukast helps control the symptoms of asthma by blocking the effects of these leukotrienes. It is especially helpful for people whose asthma symptoms are brought on by exercise or seasonal allergies such as hay fever.

Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start taking montelukast it is important that your doctor knows:

  • If you are pregnant, trying for a baby or breastfeeding.
  • If you are taking or using any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well as herbal and complementary medicines.
  • If you have ever had an allergic reaction to a medicine.
  • Before you start the treatment, read the manufacturer's printed information leaflet from inside the pack. It will give you more information about montelukast and will provide you with a full list of the side-effects which you could experience from taking it.
  • Take montelukast once every day, in the evening. The dose for adults is one 10 mg tablet. If montelukast has been prescribed for your child, the dose will depend on their age: it is 4 mg for children aged from 6 months to 5 years, and 5 mg for children aged from 6 years to 14 years.
  • The 10 mg (adult) tablet can be swallowed with a drink of water and can be taken either before or after food.
  • If your child has been prescribed tablets to take, they are cherry-flavoured chewable tablets.The tablets should preferably be taken 'on an empty stomach', which means your child should take them about an hour before a meal, or wait until two hours afterwards. They should be chewed before being swallowed.
  • If your child has been prescribed granules (in sachets), these can simply be poured into the mouth and swallowed. Alternatively if your child prefers, you can mix the granules into a small amount of cold, soft food (such as yoghurt, ice cream or mashed fruit or vegetables). It doesn't matter if montelukast granules are taken before or after meals but they should not be mixed into drinks or hot food.
  • Remember to take montelukast regularly every day, even if your asthma is well controlled. Try not to miss any of your doses but if you do forget, just take your next dose when it is due. Do not take two doses together to make up for a forgotten dose. 
  • Try to keep your regular appointments with your doctor. This is so your doctor can check on your (or your child's) progress.
  • Montelukast will not give you immediate relief if you are having an asthma attack. Your doctor will prescribe a reliever inhaler for you to use if this happens. Make sure that you keep it with you all the time in case you need to use it.
  • If you find that your asthma symptoms are getting worse, or that you need to use the reliever inhaler more regularly than usual, please contact your doctor or nurse for advice straightaway.
  • Do not smoke. Smoking causes severe irritation and damage to the lungs. It will make your condition worse and will reduce the beneficial effects of your medication.
  • If you buy any medicines, check with a pharmacist that they are suitable for you to take. Some anti-inflammatory painkillers and aspirin can make asthma symptoms worse in some people.

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains the most common ones associated with montelukast. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.

Common montelukast side-effects (these affect fewer than 1 in 10 people)
What can I do if I experience this?
Tummy (abdominal) pain, feeling sick (nausea), diarrhoeaSpeak with your doctor if this continues
HeadacheDrink plenty of water and ask your pharmacist to recommend a suitable painkiller. If the headaches continue, let your doctor know
Throat and chest infections, high temperature (fever), skin rashIf troublesome, speak with your doctor

Important: if you get any of the following symptoms, please let your doctor know straightaway. These can be a sign of a very rare but serious disorder called Churg-Strauss syndrome: flu-like symptoms, tingling feelings or numbness in your arms or legs, difficulties with breathing, and skin rash.

Taking montelukast can sometimes affect your mood or behaviour, such as causing nightmares or other sleeping problems, anxiety, depression, agitation, irritability or restlessness. If you think you (or your child) are being affected in this way, speak to your doctor for advice.

If you experience any other symptoms which you think may be due to the medicine, please speak with your doctor or pharmacist for further advice.

  • Keep all medicines out of the reach and sight of children.
  • Store in a cool, dry place, away from direct heat and light.

Never take more than the prescribed dose. If you suspect that you or someone else might have had an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.

If you are having an operation or any dental treatment, tell the person carrying out the treatment which medicines you are taking.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.

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Further reading and references